The invention relates to an analysis system comprising a main body with a surface, at least one analysis unit, consisting of at least two reservoirs placed in flow connection by at least one passage, being disposed in the main body.
Systems made up of micro-passages and known as micro-fluid systems find applications in micro-system technology in the form of miniaturised chemical or biochemical analysis systems. Microanalysis systems are used in the specific fields of research into agents, chemical diagnosis, genome analysis, environmental analysis and combined chemistry, for example. The specific feature which they offer is that they allow only very small quantities of fluid to be conveyed and manipulated. Other fields of application include micro-reactors in which chemical reactions take place, for example, or microtitre plates.
In the case of capillary electrophoresis, a sample is placed in a thin capillary, the width of which is in the order of several tens of xcexcm, and is broken down into its different components under the influence of an electric field and analysed.
Both glass and plastics are used to manufacture microstructures. WO 98/45693 A1 discloses a method of manufacturing micro-passage structures, for example. The micro-passage structures are provided by means of a base plate and a cover plate, the micro-passages being arranged in a flat surface of the base plate which is closed when a flat surface of the cover plate is placed on it. Openings through which the samples can be fed are provided in the cover plate at the ends of the micro-passages.
In order to be able to apply an electric field to the samples in the known micro-passage structures, it is necessary to insert electrodes through the openings at the ends of the micro-passages. The openings through which the samples have to be introduced and through which the electrodes also have to be inserted need to be correspondingly small, especially where a plurality of micro-passage structures is arranged on microtitre plates. However, this means that the mechanical control involved in introducing the electrodes needs to be all the more accurate. This process can hamper the process of making contacts and thereby impair operating safety.
Accordingly, it is an objective of the invention to propose an analysis system for conducting electrochemical or electrokinetic tests which is easier to operate.
This objective is achieved by the invention due to an analysis system comprising a main body with a surface, at least one analysis unit consisting of at least two reservoirs placed in flow connection by at least one passage being arranged in the main body, characterised in that two electrical conductors are disposed in the main body or on the surface, each having a first end region connected respectively to one of the at least two reservoirs, and each second end region of the conductor beings connected to a contact point on the surface of the main body or constituting this contact point. The advantage of this arrangement is that operating safety is increased because the electrical conductors and contact points are mounted on the main body of the analysis system and in particular because the contact points are mounted at a distance from the reservoirs of the analysis units so that the liquids or samples disposed in the reservoirs or passages will not be disturbed when electrodes are introduced into and removed from the reservoirs.
The main body of another embodiment of the analysis system comprises a base plate and a cover plate and the base plate and the cover plate are joined to one another by surfaces, which is of advantage because the passages and reservoirs forming the analysis unit can be made by providing recesses in one of the surfaces of the base and/or cover plate. Placing the base plate and cover plate against one another and joining them offers any easy means of closing the passages so that they can not be accessed from outside except by the reservoirs at their end regions.
In an improved embodiment in which the conductors are connected to the main body by a connection method selected from a group of connection methods consisting of bonding, vapour deposition, insertion in recesses and integral moulding, the analysis units can advantageously be made compact in design and in particular the risk of damaging the conductors can be minimised.
In another embodiment of the analysis system in which at least a part of a reservoir floor is provided in the form of the conductor or at least a part of the reservoir wall is provided in the form of the conductor, an advantage is gained because the liquid disposed in the reservoir is in contact with a sufficiently large wettable surface of the conductor to enable the current to be passed between it and the conductor, which means that contact resistance can be kept low. Having a sufficiently large conducting surface for the current to pass is an advantage given the small dimensions of the reservoirs in micro-passage structures.
Particular advantages are to be gained from another embodiment of the analysis system in which the first end region of the conductor is designed as an electrode extending between the reservoir floor and an underside of the base plate, since this allows the analysis units to be made in a simple structure. Because the electrodes run from the reservoir floor to the underside of the base plate, all conductors and their contact points can be arranged exclusively on the underside of the base plate. If the base plate is a plastics injection moulded component, the electrodes, conductors and their contact points can be made as integral components and these components placed in an injection mould so that the base plate can be made complete with electrical conductors in a single processing step.
In another design of the analysis system in which the contact points are designed to have a contact surface with a specific internal diameter and the reservoirs to have an opening with a specific internal diameter and the internal diameter of the contact surface is larger than the internal diameter of the reservoir openings, there will advantageously be much fewer errors in making contact with the contact points when voltage is applied than would normally be the case with microanalysis systems in which the reservoirs have very small openings.
Another embodiment of the analysis system in which the contact points are arranged at one common end region of the main body only offers advantages because appropriate adapters can be used to make contact with the contact points and these will have to be introduced into the analysis system from one side only.
In another embodiment of the analysis system, the conductors are made from a material selected from a group of materials consisting of metal, electrically conductive plastics, conductive paste and electrically conductive varnish, the advantage of which is that analysis systems can be produced whose electrical conductors will be sufficiently electrically conductive to enable capillary electrophoresis testing to be carried out.
Advantages are also to be had from other embodiments in which the main body is designed to the standard size of a microtitre plate or several analysis units are disposed in the layout used as standard for a microtitre plate or a predeterminable number of analysis units is provided, this number being selected from a group consisting of the numbers solving the mathematical formula 3xc3x972N where N is a whole number, or if 96 analysis units are provided, since these options will allow them to be used with standard automated equipment commonly used for microtitre plates to conduct corresponding analyses. This means that the reservoirs can be filled with samples using standardised pipette systems, for example.
If using embodiments of the analysis system in which the passage is designed as a micro-passage and the analysis unit is designed to have four reservoirs and if each two reservoirs are connected respectively to a passage and the two passages are connected respectively by a common intersecting region, there is the advantage firstly that very homogeneous flow conditions will prevail in the micro-passages due to capillary action and secondly a very small volume of a few 100 pl can be separated off in the intersecting region of the two passages for conducting capillary electrophoresis tests.
The embodiment of the analysis system in which four reservoirs are arranged in the standard layout used for a microtitre plate offers an advantage in that the standard equipment used to automate processing of microtitre plates can be used.
In accordance with another embodiment of the analysis system, a row width of the four reservoirs is the same as a half value of a row width of the analysis units, the advantage of which is that the reservoirs will be uniformly distributed on the analysis system, i.e. arranged with a maximum spacing between two immediately adjacent reservoirs.
Also of advantage is an embodiment of the analysis system in which the base plate and the cover plate are made from a plastics material, the plastics being selected from a group consisting of polymethacrylate, polycarbonate, polystyrene, polysulphone and cyclo-olefin copolymer, since these can be used to make a transparent main body for analysis systems, enabling the reactions in the passages of the analysis units to be detected.
Another embodiment of the analysis system has a base plate or cover plate which is at least partially opaque, which offers the advantage of being able to avoid any parasitic light when detecting fluorescent elements of the samples.
Finally, advantages are to be had from another embodiment of the analysis system in which the at least one passage is provided by means of recesses in at least one of the surfaces of the base plate and the cover plate is joined to at least the part of the surfaces of the base or cover plate immediately surrounding the reservoirs and passages by a joining method which affords a fluid-tight seal, the joining method being selected from a group consisting of bonding, applying polymerisable bonding agents, adhesion by temporary treatment with a solvent, heat sealing, ultrasonic welding and laser welding, since this will produce unimpaired homogeneous flow conditions in the passages.